Faculty Bibliography

PURPOSE/OBJECTIVE:To improve 0.55T T2-weighted PROPELLER lung MRI by developing a self-supervised framework for joint reconstruction and denoising. METHODS:T2-weighted 0.55T lung MRI datasets from 44 patients with prior COVID-19 infection were used. Each PROPELLER blade was split along the readout direction into two disjoint subsets: one subset for training an unrolled network, and the other for loss calculation. Following the Noise2Noise paradigm, this framework split k-space into two subsets with independent, matched noise but identical underlying signal, enabling joint reconstruction and denoising without external training references. For comparison, coil-wise Marchenko-Pastur Principal Component Analysis (MPPCA) denoising followed by parallel imaging reconstruction was performed. The reconstructed images were evaluated by two experienced chest radiologists. RESULTS:The self-supervised model generated lung images with improved clarity, better delineation of parenchymal and airway structures, and maintained high fidelity in cases with available CT references. In addition, the proposed framework also enabled further reduction of scan time by reconstructing images with adequate diagnostic quality from only half the number of blades. The reader study confirmed that the proposed method outperformed MPPCA across all categories (Wilcoxon signed-rank test, p < 0.001), with moderate inter-reader agreement (weighted Cohen's kappa = 0.55; percentage of exact and within ±1 point agreement = 91%). CONCLUSION/CONCLUSIONS:By leveraging the intrinsic data redundancy in PROPELLER sampling and extending the Noise2Noise concept, the proposed self-supervised framework enabled simultaneous reconstruction and denoising of lung images at 0.55T to address the low-SNR challenge at low-field. It holds great potential for broad use in other low-field MRI applications.

Surgical approaches to lung cancer resection are rapidly evolving, particularly for early-stage lung cancer. Advances in chest CT technology and increasing use of CT in patient care have led to detection of smaller nodules, many with ground-glass attenuation that do not require lobectomy for resection. Lung-sparing and minimally invasive techniques have been shown to result in improved patient outcomes compared with those of traditional open thoracotomy and are noninferior in terms of cancer recurrence. As more patients undergo these surgeries, it is important for radiologists to be aware of useful information for surgeons before the operation. It is helpful for radiologists to understand the indications for lung-sparing surgery and have a basic understanding of the techniques involved in video-assisted and robotic thoracic operations. Identification of the location and morphology of the tumor, as well as the pulmonary vasculature that feeds and drains the segment of lung containing the tumor is important. Also, the presence of emphysema, pulmonary fibrosis, and incomplete fissures is useful information. In addition, chest imaging is also progressing, with improvements in multiplanar reformations and three-dimensional imaging allowing for more detailed and accurate image-based localization of tumors and visualization of anatomy. Nodule localization for surgery plays an even larger role given the limited ability to palpate nodules during surgery with minimally invasive surgery approaches. Methods can involve imaging and in vivo localization, with transthoracic and bronchoscopic methods used to label a nodule. Finally, radiologists should be aware of postoperative complications and their imaging characteristics, such as suture line granulomas and bronchopleural fistulas. Supplemental material is available for this article. ^©RSNA, 2025.

PURPOSE/OBJECTIVE:Histotripsy is a non-invasive ultrasound-based tumor ablation modality. This study aims to describe the preliminary safety and short-term imaging findings related to histotripsy of liver metastases. MATERIALS AND METHODS/METHODS:All patients who underwent histotripsy for liver metastases from February 2024 to January 2025 at a single center were retrospectively reviewed. Demographic, clinical, imaging, procedural, and adverse event data were collected via chart review. Immediate post-treatment ablation zones were measured on CT and compared to pretreatment tumor size and treatment cavity size on follow-up imaging. Untreated tumors were assessed using revised RECIST criteria to evaluate for off-target effects. RESULTS:Histotripsy was performed on 56 metastatic liver tumors (most common: 32% colorectal, 18% breast) in 26 patients (54% female, age 59.1 ± 15.6y). All patients were discharged within 36 h. Immediate post-procedural ablation zones (36.6 + 13.1 mm) were larger compared to pretreatment tumors (30.5 + 18.5 mm) (p = 0.0013). One-month ablation zones (31.5 + 16.7 mm) were smaller compared to immediate post-procedural ablation zones (p = 0.00064). Two patients experienced off-target effects in non-treated liver tumors following histotripsy while off cytotoxic therapy. One patient experienced a Grade 3 complication of bacteremia requiring prolonged inpatient admission. No deaths occurred within 30 days. CONCLUSION/CONCLUSIONS:Histotripsy demonstrates a favorable safety profile for liver metastases. Observed off-target effects in untreated lesions suggest systemic immunomodulatory responses. Further investigation is warranted to elucidate patient-specific factors (e.g., tumor biology, concurrent therapies) that optimize systemic immune activation. Larger prospective studies with longitudinal immune profiling are needed to validate histotripsy's potential dual role as a locoregional therapy and immune primer in metastatic liver disease. LEVEL OF EVIDENCE/METHODS:Level 2b, retrospective cohort study.

Subsolid nodules (SSNs) are increasingly encountered in chest computed tomography (CT) imaging and clinical practice, as awareness of their significance and CT utilization grows. Either part-solid or solely ground-glass in attenuation, SSNs are shown to correlate with lung adenocarcinomas and their precursors, although a differential diagnosis is to be considered that includes additional neoplastic and inflammatory etiologies. This review discusses the differential diagnosis for SSNs, imaging and clinical features, and pathology that are helpful when making management decisions that may include PET/CT, biopsy, or surgery. Potential pitfalls in nodule characterization and management will be highlighted, to aid in managing SSNs appropriately.

BACKGROUND:Advanced-stage non-small cell lung cancer treatment has evolved with the introduction of molecularly targeted therapy, immunotherapy and combination frontline therapies. Despite these advancements, most patients experience treatment failure, resulting in poor prognosis characterized by low median progression-free survival (PFS) and overall survival (OS). Second-line chemotherapy has demonstrated minimally improved survival compared to best supportive care. Exploring new mechanisms to enhance treatment response in this patient population is critical. OBJECTIVE:This retrospective study aims to assess if there is survival benefit in a cohort of patients with stage IV lung cancer who have failed previous systemic therapy treated with pulsed electrical fields (PEF) therapy compared to a propensity-matched cohort. METHODS:A retrospective review of patients treated with PEF at three academic institutions from January 1, 2023, to July 1, 2024, yielded 41 patients with progressive stage IV non-small cell lung cancer. Tumor response was evaluated by RECIST 1.1 criteria. A propensity matched cohort of 50 patients with advanced NSCLC undergoing systemic therapy was identified. Statistical analyses, including Kaplan-Meier survival estimates and Hazard ratios, were conducted. RESULTS:The PEF-treated cohort exhibited a 1-year PFS of 63.2 % and OS of 74.3 %. In contrast, the matched cohort demonstrated a 1-year PFS of 11.8 % and OS of 33 %. The hazard ratio for PFS in the PEF group was 3.66 (p < 0.0001) and for OS was 3.5 (p = 0.0007), indicating a significant survival advantage for patients receiving PEF. CONCLUSION/CONCLUSIONS:This study suggests that PEF therapy may be associated with significantly improved PFS and OS in patients with progressive stage IV non-small cell lung cancer compared to the matched cohort. Prospective controlled studies are required to confirm these preliminary findings, to better understand the mechanism of action of PEF, and to identify which patient populations would best benefit from this therapy.

Acute respiratory illness is one of the leading causes of morbidity and mortality amongst infectious diseases worldwide and a major public health issue. Even though most cases are due to self-limited viral infections, a significant number of cases are due to more serious respiratory infections where delay in diagnosis can lead to morbidity and mortality. Imaging plays a key role in the initial diagnosis and management of acute respiratory illness. This document reviews the current literature concerning the appropriate role of imaging in the diagnosis and management of the immunocompetent adult patient initially presenting with acute respiratory illness. Imaging recommendations for adults presenting with asthma or chronic obstructive pulmonary disease exacerbations are discussed. Finally, guidelines for follow-up imaging in suspected pneumonia cases to ensure occult malignancy is not overlooked. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or intermediate, experts may be the primary evidentiary source available to formulate a recommendation.

This document reviews the evidence supporting different imaging modalities and techniques used to evaluate patients with a history of lung cancer. It focuses on the imaging evaluation of patients treated for stage I-III non-small-cell lung cancer and small-cell lung cancer, whether using individual modalities or combinations. Guidelines for both routine surveillance of stage I-III lung cancer and for the evaluation of suspected recurrence or disease progression are provided. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

PURPOSE/OBJECTIVE:To assess the safety and feasibility of Pulsed Electrical Fields (PEF) ablation in various organs and patient populations. MATERIALS AND METHODS/METHODS:This multi-center, retrospective study collected data from five academic medical centers on patients undergoing percutaneous PEF ablation, with a minimum of 30 days follow-up. Parameters assessed included demographics, treatment specifics, immediate adverse events, and survival rates. Procedures used CT or ultrasound guidance with a 19-gauge insulated needle and PEF probe. RESULTS:This study included 155 patients with a mean age of 60.7 years, predominantly with lung cancer (77/155). Most patients 85 % (131/155) had stage IV disease. The mean hospital stay post PEF was 0.3 days, with most discharged the same day. In lung procedures adverse events of pneumothorax occurred in 21.5 % of lung procedures, with 11.3 % requiring chest tube placements. No adverse events were observed in liver procedures. The 1-year overall survival rate for the entire cohort was 74.6 %, with patients with colorectal cancer having the highest survival rate of 89.7 %, and patient with sarcomas lowest at 18.0 %. CONCLUSION/CONCLUSIONS:Percutaneous PEF is feasible to be performed across a variety of organs. Although difficult to compare with other modalities, this data suggests that PEF ablation is relatively safe. However, further prospective studies with larger sample sizes and comprehensive imaging are needed to confirm these findings and establish efficacy.

BACKGROUND:Postacute Covid-19 patients commonly present with respiratory symptoms; however, a noninvasive imaging method for quantitative characterization of respiratory patterns is lacking. PURPOSE/OBJECTIVE:To evaluate if quantitative characterization of respiratory pattern on free-breathing higher temporal resolution MRI stratifies patients by cardiopulmonary symptom burden. STUDY TYPE/METHODS:Prospective analysis of retrospectively acquired data. SUBJECTS/METHODS:A total of 37 postacute Covid-19 patients (25 male; median [interquartile range (IQR)] age: 58 [42-64] years; median [IQR] days from acute infection: 335 [186-449]). FIELD STRENGTH/SEQUENCE/UNASSIGNED:0.55 T/two-dimensional coronal true fast imaging with steady-state free precession (trueFISP) at higher temporal resolution. ASSESSMENT/RESULTS:Patients were stratified into three groups based on presence of no (N = 11), 1 (N = 14), or ≥2 (N = 14) cardiopulmonary symptoms, assessed using a standardized symptom inventory within 1 month of MRI. An automated lung postprocessing workflow segmented each lung in each trueFISP image (temporal resolution 0.2 seconds) and respiratory curves were generated. Quantitative parameters were derived including tidal lung area, rates of inspiration and expiration, lung area coefficient of variability (CV), and respiratory incoherence (departure from sinusoidal pattern) were. Pulmonary function tests were recorded if within 1 month of MRI. Qualitative assessment of respiratory pattern and lung opacity was performed by three independent readers with 6, 9, and 23 years of experience. STATISTICAL TESTS/METHODS:Analysis of variance to assess differences in demographic, clinical, and quantitative MRI parameters among groups; univariable analysis and multinomial logistic regression modeling to determine features predictive of patient symptom status; Akaike information criterion to compare the quality of regression models; Cohen and Fleiss kappa (κ) to quantify inter-reader reliability. Two-sided 5% significance level was used. RESULTS:; CV: 0.072, 0.067, and 0.058). Respiratory incoherence was significantly higher in patients with two or more symptoms than in those with one or no symptoms (0.05 vs. 0.043 vs. 0.033). There were no significant differences in patient age (P = 0.19), sex (P = 0.88), lung opacity severity (P = 0.48), or pulmonary function tests (P = 0.35-0.97) among groups. Qualitative reader assessment did not distinguish between groups and showed slight inter-reader agreement (κ = 0.05-0.11). DATA CONCLUSION/CONCLUSIONS:Quantitative respiratory pattern measures derived from dynamic higher-temporal resolution MRI have potential to stratify patients by symptom burden in a postacute Covid-19 cohort. LEVEL OF EVIDENCE/METHODS:3 TECHNICAL EFFICACY: Stage 3.